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Running on Empty: My First Attempt at Fasted Cardio

This morning was my third day doing fasted cardio. If you’re not familiar with fasted cardio, it’s exactly what its name implies—performing cardio first thing in the morning on an empty stomach. The reason I started implementing this technique is because I reached out to Tracy Hess, an IFBB pro who trains at my gym, to devise a meal plan for me last week. To my (pleasant) surprise, she not only developed a meal plan for me but also gave me a resistance training program and advised me to do fasted cardio five days a week for 45 minutes each session.

I’ve read about fasted cardio before, and I know it’s a topic of much debate in the fitness and bodybuilding community. The theory behind fasted cardio is that you’ll burn more fat working out in a fasted state compared to working out after you eat. This is because when your body is in a fasted state, it has a low or no supply of glycogen (glycogen is the stored carbohydrates that the body prefers to use for exercise), therefore your body is able to tap into its fat stores for energy faster, meaning you burn a greater percentage of fat during your workout.

(*Note: You’ll burn the same amount of calories performing cardio in a fasted and non-fasted state; where those calories come from (fat vs. carbs) is the idea behind fasted cardio.)

Why I (Finally) Decided to Give Fasted Cardio a Try

There are both pros and cons to fasted cardio—which is why it continues to be heavily debated. I had previously considered adding it to my training routine until I read the facts against it (more on that later) and weighed the thought of getting up early to work out with no immediate energy source (i.e., food) present. It seemed like skipping fasted cardio was a no-brainer.

After meeting with Tracy and going over my goals, I decided to give fasted cardio a shot. I not only have Tracy’s physique and expert knowledge to back up my decision; I also have the results I’ve seen with her clients. One of them recently competed in her first bikini competition—and won!

When I went over the meal plan and training program with Adam (my trainer), he said that the fasted cardio will make me tired, but that it will definitely help get rid of the extra fat around my stomach and hips, which is exactly what I need. That’s also one of the pros of fasted cardio: it helps get rid of “stubborn” fat from the hips, thighs, and butt. (You can read more about how fasted cardio helps get rid of stubborn fat here.)

While fasted cardio increases your body’s ability to burn fat, specifically from “trouble” spots, it does have one major drawback: it increases the breakdown of muscle tissue.

Training in a fasted state puts stress on the body and because there is no immediate source of glycogen present your body begins to break down muscle—along with fat—for fuel. This is the major drawback of fasted cardio, especially since muscle is metabolically active (meaning it helps you burn more calories, even when you’re not physically active). In a way, fasted cardio is a double-edged sword: it helps you lose stubborn body fat, but it also helps you lose muscle tissue, which will decrease your metabolic rate. (Not to mention you worked hard for that muscle, the last thing you want to do is lose it!)

Luckily there is a way to counteract this effect: branched chain amino acids (BCAAs). According to various studies, supplementing with BCAAs 10 – 15 minutes before performing fasted cardio will help suppress the breakdown of muscle.

I’ve worked very hard to build the muscles in my legs and butt these past few months and I’m extremely happy with the results I’ve gotten. I was afraid fasted cardio would take all of that beautiful muscle growth away from me…so today I picked up some BCAAs at GNC.

I’ve only done three fasted cardio sessions thus far, and I doubt not having the BCAAs beforehand caused me significant muscle loss. However, I don’t want to risk it and will be supplementing with BCAAs from now on.

My Experience with Fasted Cardio (So Far)

Though it’s only been three days, I do want to say that fasted cardio is easier than I thought (hopefully I didn’t just jinx myself). I thought it would be hard to get up and work out for 45 minutes every morning, but knowing that this could help me reach my goal and target the areas where I WANT to lose weight keeps me going. Some other benefits I’ve experienced include having more energy after my workouts and feeling more accomplished. Plus, there is now a longer rest period between my cardio and weight training sessions, so I don’t feel like I’m going from one workout to the next.

On the flip side, I can see how this may get old pretty fast. I noticed that I’m tired earlier in the night. Part of this is good because I wanted to improve my sleep, and knowing that I have to work out first thing in the morning motivates me to get to bed earlier. And since I’m going to bed earlier, I don’t have the time or desire to snack on something sweet, which was a major flaw in my diet.

With the mornings getting colder and colder, however, I can see that it could get harder and harder to get out of bed in the morning. Even this morning I stayed in bed a few minutes longer, debating if I should skip the fasted cardio or not. In the end, I know I have a goal I want to reach and that I need to stay consistent if I want this to get easier and become a regular habit. And once I got up and hopped on the elliptical, I knew I made the right decision. After the first five minutes I was ready to keep going, and I even went a few minutes longer.

It’s still early and only time will tell if fasted cardio is right for me. I plan to do a follow-up post in the next couple weeks to update you on my progress and any issues I’ve experienced.

What do think about fasted cardio? Have you tried it? What was your experience like? Let me know in the comments!

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Hi! I'm Kimberlee. I’m a writer & social media manager who enjoys working out, cooking and eating healthy food (along with the occasional indulgence), exploring new places, and having fun. I’m passionate about living a healthy & fit lifestyle, and I hope to inspire you to do the same. Join me in living a BeYOUtifully Fit life!